import matplotlib.pyplot as plt
import numpy as np


def plot():
    X = np.linspace(-1, 2, 256)
    Y = X / 2
    Y_2 = (1-X)/2
    Y_3 = np.linspace(-0.5, 1, 256)
    X_3 = np.linspace(0.5, 0.5, 256)

    plt.plot(X, Y)
    plt.plot(X, Y_2)
    plt.plot(X_3, Y_3)


    plt.xlabel(r'$x_1$')
    plt.ylabel(r'$x_2$')
    plt.show()


if __name__ == '__main__':
    plot()
